This invention concerns torque limiters which are well known devices which act to produce an overload release in a rotary drive train when the torque transmitted exceeds a predetermined level, in order to prevent damage to components in the drive train.
Resettable torque limiters are also well known in which drive balls are installed in detent pockets and held therein by a plunger urged against the drive ball by spring pressure. When a predetermined maximum torque is reached, the drive ball can force the plunger away and allow the drive ball to climb out of the pocket allowing relative rotation of two interfit parts to interrupt the driving connection therebetween.
In conventional practice, grease is applied to the wearing components by injection into a passage drilled through the plunger to the drive ball engaged with the plunger end, and passages extending radially out past a bushing to reach various wear components.
However, in prior designs grease does not flow past the drive ball to the detent pocket without release of the torque limiter since the drive ball normally blocks the grease flow until the torque limiter releases. Grease flow past the bushing is limited due to the limited clearance.
For high torque release settings, it is difficult to manually trip the limiter for routine maintenance purposes.
In such torque limiters there are sometimes also heavily preloaded bearings supporting one interfit part on the other. Normally these parts do not relatively rotate, but both parts rotate together since connected together by the torque limiter drive ball, and these bearings become dry as the grease migrates out over time due to centrifugal force generated by rotation together of the interfit parts. Due to their location, these bearings are not able to be greased, except when the torque limiter is released.
It is an object of the present invention to provide improved lubrication for a resettable torque limiter of the type described above by providing enhanced distribution of grease to the wearing components.